/Engine/Source/Runtime/InteractiveToolsFramework/Public/InteractiveToolQueryInterfaces.h
IInteractiveToolNestedAcceptCancelAPIprovides an API for a Tool to publish intent and ability to Accept or Cancel sub-operations. For example in a Tool that has an editable active Selection, we might want the Escape hotkey to Clear any active selection, and then on a second press, to Cancel the Tool. This API allows a Tool to say "I can consume a Cancel action", and similarly for Accept (although this is much less common).
class IInteractiveToolNestedAcceptCancelAPI